Bonneville America Forums Forums Technical Forums Performance Mods The Carnage of Pinging

I've never really posted anything here, just added to conversations from time to time, but here it goes.

So here we are with busted pistons, but first a back story.
The past three riding seasons have been going good. The sound that I was hearing up to the point of things going kaboom I chalked it up to the floats on the carbs (36mm CRII's) jittering when the engine was under load at speed (about 60-75 mph). I would experience a rattling sound and loss of power while keeping the same throttle position. Thinking the carbs were getting starved of fuel from lack of venting, I would open the fuel filler to equalize the pressure. After a little while, the engine would pick back up and we (my '04 Speedy and I) would continue the ride. This seemed to work for quite a while.
I had the 904 big bore kit installed at my dealership when I was stationed in Florida. Six years ago, I got orders and move up to Minot, North Dakota. Which brings me to problem #1: I put in the higher compression pistons in FL (12.1:1). Instead of the stock 10.5:1. This leads to problem #2: higher octane fuel is readily available in FL...not so much in ND. The highest I have seen up here is 93, but that is only in the bigger towns. You would be hard pressed to find that in some of the tiny towns around here. 91 or even 89 would be the highest they would carry.
This all culminates to the events on 20 May. I was hosting the annual beginning of season safety ride for my squadron. I was riding tail gunner (very back) to observe and give any corrections to those that I may see having trouble riding in a group situation. We were about 20 miles from town and the engine started doing what I explained above. I took the fuel cap off and waited a bit...nothing...still losing power and speed. Downshifted to try to keep up, the rattle got real bad. As soon as I heard how loud it was, I shut the throttle and pulled over immediately. I came to a stop and the engine quit and I was greeted with the big red glow of the engine oil pressure light. I attempted once to restart the engine and when I heard the starter spinning at a much faster rate (like the engine didn't have any compression), I stopped and called for a ride (which promptly ended mine).

So below are the pictures of what I found after pulling the head. This of course is due to pinging. I have never heard an engine do this before even I know what it is. So now both myself and my wallet are getting an education.

Left piston in cylinder


Right piston in cylinder
http://s164.photobucket.com/user/joejoetoy/media/Right%20Piston%20in%20cylinder.jpg

Left piston out of cylinder


Right piston out of cylinder


Left piston measurement


Right piston inside measurement


Right piston outside measurement


Luckily I'm very certain that the pieces have exited through the exhaust. The rings were burnt, but no pieces were missing.
At least I get to address some (much) smaller issues that I've been meaning to get done on the bike as well. Change the gearing, center mount the battery, rewire a few things, repaint the header wrap and put the Scypters back on.

I think I figured out the pic thing.

Left piston in cylinder
[image][/image]

Right piston in cylinder
[image][/image]

Left piston out of cylinder
[image][/image]

Right piston out of cylinder
[image][/image]

Left piston measurement
[image][/image]

Right piston inside measurement
[image][/image]

Right piston outside measurement
[image][/image]

That is what I like a positive attitude. Sorry for your pain.

Well it is unfortunate that I'll be missing quite a bit of the riding season. I was posting more for informative reasons. I tried searching for pinging type posts after it happened to see what others have experienced. I couldn't find much. So thought that I would share with some pics as to what can happen. If this can help someone who is experiencing the same thing, maybe he/she can hold out for that gas station with the 96 octane. Or put some booster in the tank (I don't recommend for long term use).

IT WON'T BE A BIG PROBLEM IF SOMEONE IS RIDING A STOCK BIKE BUT YOUR 12:1 PISTONS COMPRESSION RATIO IS FAR TO HIGH W/O 91+ OCTANE. ADD 100+ OUTSIDE TEMPS AND YOU HAVE A COMBINATION FOR A DETONATED ENGINE

Any airport for light civilian craft has all the 100 octane non ethanol gas you want. Use it as an additive with the best local pump gas you can find and you should be good to go, as well as a lot more economical than additives.. A little late for your motor now, sorry.

This is why I always ran 10.5:1.

I just pull up to the local airport in a junker, but street legal pickup that I keep a internally clean 55 gal barrel strapped up and buy what I can afford. Once I established an initial relationship at the airport, it's been easy, they even accept cash. If they land and fuel Lear jets, look for a smaller drome. If I lived in the King Corn Belt, I would probably buy even more, their pump gas really sucks.

I have the same JE 12:1 pistons and the same crappy gas options. As getting (consistently) high octane fuel became increasing difficult in WI and converted the bike to just run on 93 E10 or higher. the mileage sucks but the detonation problems went away as well.
I have looked into the bores several times and so far all appears well (borrowed a bore scope from work).

FWIW when I assembled my motor I took a file to the sharp edges of the piston domes. That may be helping in avoiding hot spots.

Micah, didn't you also retard the timing at the pickup coil?